1. Field of the Invention
The present invention relates to a color charge-coupled device (CCD). More particularly, the present invention relates to a color CCD that simplifies a fabrication process and improves a yield by improving the color filter construction.
2. Description of the Related Art
A conventional color CCD will be explained hereinafter with reference to the accompanying drawings. FIG. 1A is a view illustrating a layout of a conventional color CCD, and FIG. 1B is a sectional view illustrating a conventional color CCD construction.
Referring to FIG. 1B, the conventional color CCD includes a plurality of photo diodes 11 formed on a semiconductor substrate 10 at a predetermined interval, and a vertical charge coupled device VCCD 12 formed vertically between photo diodes 11 for transferring a signal produced by photoelectric conversion in the photo diodes 11 in one direction. An insulation layer 16 is formed over the entire surface of the semiconductor substrate 10 in which the photo diodes 11 and the VCCD 12 are located, and a plurality of polygates 17 are formed on the insulation layer on an upper surface of the VCCD 12 for transferring the signal produced in the photo diodes 11 to the VCCD 12, or for transferring the signal charge transferred to the VCCD 12 in one direction. A metal shielding layer 13 for shielding light is deposited over the polygates 17 except for those areas over light receiving regions in which the photo diodes 11 are located. A flat insulation film 18 is deposited over the entire surface of the semiconductor substrate 10 including the metal shielding layer 13. A color filter layer 14 of either red, green, or blue is then formed over each photo diode 11 corresponding to a pixel. A top coating layer 19 is deposited on the color filter layer 14. Finally, a microlens 15 is formed on the top coating layer for concentrating light on the photo diodes 11.
In the conventional color CCD, the color filter layer 14 of red, green, and blue separates the spectrum of incident light and allows only the light of each predetermined wavelength to be incident to the photo diodes 11.
The metal shielding layer prevents the light from being incident anywhere other than the photo diodes 11. The incident light described above is converted into an electric signal in the photo diodes 11 and transferred out to a processor. While the color CCD has many uses, manufacturing the conventional color CCD can be difficult and expensive.
The manufacturing process is complicated by the required three step dyeing process that is used to form the color filter layer. It is difficult to maintain uniformity of the colors during the dyeing process. Moreover, it is difficult to manufacture highly integrated, high density charge coupled devices with conventional multiple masking techniques, because of the more intricate masks required for the process and the tendency of the dyes to mix. Accordingly, mask mis-alignment makes it more difficult to maintain color separation.